D-12P (D-12) Medium-Voltage Switchgear 6(10) kV

The D-12P (D-12) series is a family of modular metal-clad 6-10 kV medium-voltage cubicles designed for the reception, distribution, and switching of three-phase 50 Hz power in systems with an isolated or grounded neutral (via an arc-suppression coil / Petersen coil or an active resistor). The design focuses on safe operation, easy maintenance, and high equipment availability.

Each panel enclosure is made of steel with an anti-corrosion aluzinc coating, and the internal volume is divided into independent compartments: withdrawable unit (breaker truck), cable, busbar, and relay/control. Solid partitions and individual pressure-relief ducts confine internal-arc effects to a single compartment, directing hot gases upward and protecting personnel at the front.

To enhance reliability, mechanical and electromechanical interlocks prevent incorrect operations, while secondary circuits are routed in segregated metallic cable ducts with single-point grounding - improving EMC immunity and simplifying the deployment of digital protection IEDs, including those supporting IEC 61850. Unified D-12P assemblies allow flexible configuration to project requirements and painless future upgrades of the switchgear.

D-12P is suitable for installation both in permanent indoor switchgear rooms and in factory-built modular e-houses. The design ensures convenient access to fastening points, cable terminations, and inspection points, reducing commissioning time and service downtime.

Scope of use

D-12P switchgear is applied at generation sites, distribution networks, and industrial consumers:

Indoor switchgear of package substations (PTS) and urban 6-10 kV distribution points;
substations and electrical facilities of industrial plants;
auxiliary medium-voltage switchgear of TPP/HPP/CCGT units;
utilities, waterworks, pumping stations, data centers;
modular substations (factory-built) and retrofit of existing MV rooms.

Service conditions

Environmental conditions - EN/IEC 60721-3-3; operating temperature -25…+40 °C;
Altitude - up to 1000 m (above that - insulation and cooling to be verified by calculation);
Non-hazardous indoor atmosphere, free of conductive dust and corrosive vapors (typical industrial environment per EN/IEC 60721-3-3);
Degree of protection - IP31 per EN/IEC 60529 (higher IP on request);
Maintenance access options - single-sided or two-sided, depending on lineup layout.

Design features

Four-compartment architecture: withdrawable breaker ⋅ busbar ⋅ cable ⋅ relay/control;
Pressure-relief flaps on each duct; position limit switches / photoelectric sensors for status signaling;
Mechanical/electromagnetic interlocks in line with IEC safety interlocking practices;
Secondary circuits in metallic cable ducts - high EMC immunity;
Unified assemblies - fast adaptation to project needs and future modernization.

Configuration and options

12 kV vacuum circuit-breaker (manufacturer per project), CTs/VTs, ZnO surge arresters;
Functional cubicles: incoming, bus-section, feeders, metering/measuring, VT;
Cable entry top/bottom; maintenance - single-sided/two-sided;
Protection IEDs with AR/ATS/UFLS, IEC 61850 (MMS/GOOSE) - per specification;
Options: arc-flash sensors, relay-compartment heaters, increased IP, retrofit-ready design.

Reliability and service life

Internal-fault effects confined within the affected compartment - adjacent panels remain operational;
Vacuum breakers class M2/E2/C2 - endurance up to 30,000 O-C cycles;
Steel body with aluzinc and powder coating - durable corrosion protection;
Consistent interlocking logic and structured wiring - faster service and diagnostics.

Technical data

Rated voltage, kV	6; 10
Highest system voltage, kV	7.2; 12
Rated current of main circuits, A	630; 1250; 1600; 2000; 2500; 3150
Rated busbar current, A	1250; 1600; 2500; 3150
Short-time withstand current (3 s), kA	20; 25; 31.5
Peak (dynamic) withstand current (1 s), kA	51; 64; 81
Maintenance access	single-sided, two-sided
Insulation level per IEC 60071-1:2019	standard
Environmental conditions	EN/IEC 60721-3-3
Degree of protection	IP31 (EN/IEC 60529)
Overall dimensions, mm - width - depth - height	650; 750; 900; 1000 1300; 1450; 1600 2300

We offer documentation for manufacturing D-12P switchgear:

Tender package. Single-line diagrams, inquiry sheets, and technical description for procurement and feasibility review.

Working drawings and 3-D models. Layout/assembly, BOM, secondary schematics, and cable schedules - tailored to your production.

Contract manufacturing of assemblies. We arrange enclosure/mechanism production with partners; you handle assembly, installation, and routine factory tests.

Adaptation and integration. Drop-in replacement cubicles for existing busbars and secondary circuits; compatibility with third-party equipment.